Cement compositions may be used in a variety of subterranean operations. For example, in subterranean well construction, a pipe string (e.g., casing, liners, expandable tubulars, etc.) may be run into a wellbore and cemented in place. The process of cementing the pipe string in place is commonly referred to as “primary cementing.” In a typical primary cementing method, a cement composition may be pumped into an annulus between the walls of the wellbore and the exterior surface of the pipe string disposed therein. The cement composition may set in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement (i.e., a cement sheath) that may support and position the pipe string in the wellbore and may bond the exterior surface of the pipe string to the subterranean formation. Among other things, the cement sheath surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protect the pipe string from corrosion. Cement compositions also may be used in remedial cementing methods, for example, to seal cracks or holes in pipe strings or cement sheaths, to seal highly permeable formation zones or fractures, to place a cement plug, and the like.
A broad variety of cement compositions have been used in subterranean cementing operations. In some instances, set-delayed cement compositions have been used. Set-delayed cement compositions are characterized by remaining in a pumpable fluid state for an extended period of time (e.g., at least about 1 day to about 2 weeks or more). When desired for use, the set-delayed cement compositions should be capable of being activated whereby reasonable compressive strengths are developed. For example, a cement set activator may be added to a set-delayed cement composition whereby the composition sets into a hardened mass. Among other things, the set-delayed cement composition may be suitable for use in wellbore applications, for example, where it is desired to prepare the cement composition in advance. This may allow, for example, the cement composition to be stored prior to its use. In addition, this may allow, for example, the cement composition to be prepared at a convenient location and then transported to the job site. Accordingly, capital expenditures may be reduced due to a reduction in the need for on-site bulk storage and mixing equipment. This may be particularly useful for offshore cementing operations where space onboard the vessels may be limited.
Drilling requires the use of drilling fluid or as it is also known, drilling mud. One problem associated with drilling may be the undesirable loss of drilling fluid to the formation. Such lost fluids typically may go into, for example, fractures induced by excessive mud pressures, into pre-existing open fractures, or into large openings with structural strength in the formation. This problem may be referred to as “lost circulation,” and the sections of the formation into which the drilling fluid may be lost may be referred to as “lost circulation zones.” In addition to drilling fluids, problems with lost circulation may also be encountered with other treatment fluids, for example, spacer fluids, completion fluids (e.g., completion brines), fracturing fluids, and cement compositions that may be introduced into a well bore.
The loss of treatment fluids into the formation is undesirable, inter alia, because of the expense associated with the treatment fluid lost into the formation, loss of time, in extreme conditions, well abandonment. Treatment fluid replacement does not just create operation downtime, but may also require additional fluid storage, additional manpower, and additional equipment. In addition to the increased operating expenses, fluid replacement may create additional worksite problems such as higher environmental burdens and the inability to recycle fluids and materials once their respective portion of the operation has been completed.